BirdAnalyst
Species · BCR 33 · BBS 2025 Release · 1966–2024

Bell's Sparrow In Sonoran and Mojave Deserts

All regionsSonoran and Mojave DesertsGeneralists

Bell's Sparrow in Sonoran and Mojave Deserts has edged up: up 23% on the route-weighted index since 1972.

+23%Since 1972TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
16Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
54YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

No notable trend signals for Bell's Sparrow in Sonoran and Mojave Deserts. See the full index history below.

Bell's Sparrow In Sonoran and Mojave Deserts Population Forecast

If the recent trend holds, Bell's Sparrow in Sonoran and Mojave Deserts is projected to rise about 38% by 2029 — from 0.83 in 2024 to a central estimate of 1.1 (95% range 0.00–2.4). A 5-year backtest shows a typical error of ±945.2%, with 100% of held-out values landing inside the 95% band.

+38%Change by 2029TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
1.1Projected 2029 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–2.495% range95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
±945.2%Backtest errorBacktest errorTypical error when we hold out the most recent years, forecast them, and compare to what actually happened. Lower means a more trustworthy projection.Full methodology →
If the recent trend holds, Bell's Sparrow in Sonoran and Mojave Deserts is projected to rise about 38% by 2029 — from 0.83 in 2024 to a central estimate of 1.1 (95% range 0.00–2.4). A 5-year backtest shows a typical error of ±945.2%, with 100% of held-out values landing inside the 95% band.19692029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →95% low95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →95% high95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
20251.10.002.4
20261.10.002.4
20271.10.002.4
20281.10.002.4
20291.10.002.4

Routes In Sonoran and Mojave Deserts

Routes recording Bell's Sparrow in Sonoran and Mojave Deserts.
Recent countThe raw number of individuals recorded on this route in its most recent survey year. A single-route tally, not a trend.Full methodology →
Willow Springs 2CALIFORNIA162024
Calif CityCALIFORNIA122015
GoldstoneCALIFORNIA102009
OnyxCALIFORNIA52015
Ash MeadowsNEVADA42015
BarstowCALIFORNIA31998
Lucerne ValCALIFORNIA32024
Ft IrwinCALIFORNIA31981
Willow SpgsCALIFORNIA21981
InyokernCALIFORNIA22024
Lane MtnCALIFORNIA21973
Kelso ValleyCALIFORNIA22024
Joshua TreeCALIFORNIA21981
LenwoodCALIFORNIA12012
PearblossomCALIFORNIA12024
Lone PineCALIFORNIA12024

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.